The pain in the upper left part of the cardiothoracic fossa can be caused by coronary heart disease, trauma, costochondritis, pleurisy and so on. 1. Coronary heart disease: coronary artery lumen narrowing or occlusion, emotional excitement, tension, anxiety, strenuous exercise, easy to increase myocardial oxygen consumption, resulting in insufficient local blood supply, can trigger angina attack, manifested as precordial pain, tightness, and in severe cases, dyspnea and other symptoms. 2. Trauma: local soft tissue injury or rib fracture caused by impact or extrusion, which can be manifested as chest pain, chest tightness, coughing or deep breathing pain can be aggravated, and localized skin lesions or bruises can be seen. 3. Costal chondritis: cartilage lesions at the junction of ribs and sternum, causing localized swelling and pain, which may be aggravated when pressed. 4. Pleurisy: inflammation occurring in the pleural cavity, chest pain, chest tightness and other uncomfortable symptoms, severe cases are also accompanied by dyspnea, tuberculous pleurisy can also be accompanied by low-grade fever, night sweats, fatigue and other systemic symptoms. The left upper part of the chest fossa pain can also be seen in other diseases, it is recommended that patients go to the regular hospital in a timely manner, so as not to delay the condition.